Previous research from this laboratory has supported the concept that ribosomal protein-synthesizing systems in the brain are unusually sensitive to environmental alterations and regulatory factors. The present project is concerned with the metabolic and physicochemical bases for this instability. One process which may be involved in this phenomenon is the susceptibility of brain ribosomal proteins to phosphorylation in response to neurotransmitter agents and other substances which activate adenylate cyclase systems in this organ. During the current year, we plan detailed investigations of the nature of this phosphorylation process and its regulation. In addition, studies will be conducted on the influence of alterations in ribosomal protein phosphorylation on ribosome functions in brain protein synthesis.